Question

A book of mass 800 g is pushed off of a shelf with a force of 20 N. Given that the book falls with an initial velocity of 2 m/s, calculate the time of contact between the book and the hand pushing it.​

Answer 1

F = Δp / Δt ⇒ t = Δp / F (To get the time of contact, we divide the change in momentum by the applied force)

Since the book was stationary before we pushed it, the initial momentum is 0. Hence the change in momentum will just be the value of the final momentum.

Δp = mv

t = mv / F = (0.8 kg * 2 m/s) / 20 N = 0.08 s

Step-by-step explanation: